In recent years, a technique to epitaxially grow a Si-based crystal such as a SiGe crystal, etc., on a Si-based substrate or a Si-based crystal layer is often used for fabricating a semiconductor device.
For example, in a technique described in JP-A-2006-13428, by epitaxially growing a SiGe crystal having a lattice constant larger than that of a Si crystal at a position sandwiching a channel region of a p-type transistor, a compressive stress is generated in the channel region and thereby straining the channel region. As a result, it is possible to improve carrier (hole) mobility in the channel region, thereby improving an operating speed of the p-type transistor.